Effects of powdered Montmorency tart cherry supplementation on

Transcription

Effects of powdered Montmorency tart cherry supplementation on
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
DOI 10.1186/s12970-016-0133-z
RESEARCH ARTICLE
Open Access
Effects of powdered Montmorency
tart cherry supplementation on acute
endurance exercise performance in
aerobically trained individuals
Kyle Levers1, Ryan Dalton1†, Elfego Galvan1†, Abigail O’Connor1†, Chelsea Goodenough1†, Sunday Simbo1,
Susanne U. Mertens-Talcott2, Christopher Rasmussen1, Mike Greenwood1, Steven Riechman3, Stephen Crouse4
and Richard B. Kreider1*
Abstract
Background: The purpose of this study was to determine whether short-term supplementation of a powdered
tart cherry supplement prior to and following stressful endurance exercise would affect markers of muscle damage,
inflammation, oxidative stress, and/or muscle soreness.
Methods: 27 endurance-trained runners or triathlete (21.8 ± 3.9 years, 15.0 ± 6.0 % body fat, 67.4 ± 11.8 kg) men
(n = 18) and women (n = 9) were matched based on average reported race pace, age, body mass, and fat free mass.
Subjects were randomly assigned to ingest, in a double-blind manner, capsules containing 480 mg of a rice flour placebo
(P, n = 16) or powdered tart cherries [CherryPURE®] (TC, n = 11). Subjects supplemented one time daily (480 mg/day) for
10-d, including race day, up to 48-hr post-run. Subjects completed a half-marathon run (21.1 km) under 2-hr (111.98 ± 11.
9 min). Fasting blood samples and quadriceps muscle soreness ratings using an algometer with a graphic pain rating
scale were taken pre-run, 60-min, 24 and 48-h post-run and analyzed by MANOVA with repeated measures.
Results: Subjects in the TC group averaged 13 % faster half-marathon race finish times (p = 0.001) and tended to have
smaller deviations from predicted race pace (p = 0.091) compared to P. Attenuations in TC muscle catabolic markers
were reported over time for creatinine (p = 0.047), urea/blood urea nitrogen (p = 0.048), total protein (p = 0.081), and
cortisol (p = 0.016) compared to P. Despite lower antioxidant activity pre-run in TC compared to P, changes from
pre-run levels revealed a linear increase in antioxidant activity at 24 and 48-h of recovery in TC that was statistically
different (16–39 %) from P and pre-run levels. Inflammatory markers were 47 % lower in TC compared to P over time
(p = 0.053) coupled with a significant difference between groups (p = 0.017). Soreness perception between the groups
was different over time in the medial quadriceps (p = 0.035) with 34 % lower pre-run soreness in TC compared to P.
Over the 48-h recovery period, P changes in medial quadriceps soreness from pre-run measures were smaller
compared to TC.
Conclusion: Results revealed that short-term supplementation of Montmorency powdered tart cherries surrounding
an endurance challenge attenuated markers of muscle catabolism, reduced immune and inflammatory stress, better
maintained redox balance, and increased performance in aerobically trained individuals.
Keywords: Recovery, Antioxidants, Anti-inflammatory, Muscle damage
* Correspondence: [email protected]
†
Equal contributors
1
Department of Health and Kinesiology, Exercise and Sport Nutrition
Laboratory, Texas A&M University, College Station, TX 77843-4243, USA
Full list of author information is available at the end of the article
© 2016 Levers et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Background
Acute bouts of strenuous aerobic exercise facilitate a
stress response characterized by mechanical muscle damage, oxidative stress, and inflammation that parallels the
physiological stress response associated with many adverse
traumatic cardiovascular events and illnesses [1–3]. As a
result, this type of long duration mechanical muscle stress
and high oxidative metabolic demand [4], significantly
increases free radical production beyond the capacity of
the endogenous antioxidant systems. Ultimately, this increase facilitates excessive cell damage, altered cell signaling [5–7], decreased cellular performance [5–8], lipid
peroxidation, oxidation of proteins and glutathione, and
subsequent DNA damage [3, 9]. Exercise-induced muscle
soreness is indirectly related to inflammation as a product
of high nociceptor and mechanoreceptor sensitivity to
potent metabolites released during muscular degeneration
[10, 11].
The use of antioxidant supplements, such as vitamins C
[12–15] and E [4, 14, 15], in athletic applications to help
fortify the body’s endogenous antioxidant response has
spurred some success. However, vitamins C and E (independently or in combination with N-acetylcysteine, βcarotene, or α-lipoic acid) remain controversial due to conflicting reports of effectiveness [3, 16–19] with potential
post-exercise pro-oxidant effects on muscle protein anabolism [20–22], endogenous antioxidant capacity [22], and
mitochondrial biogenesis [23].
More recent nutritional research has focused on the
antioxidant effects of functional foods containing high
concentrations of phenolic compounds such as flavonoids
and anthocyanins. It is proposed that these may act synergistically with other compounds contained within the food
to provide an overall aerobic exercise recovery benefit [4,
24]. A wide variety of antioxidant and polyphenolcontaining functional foods such as grape extract [25],
chokeberries [26], and blueberries [8] have shown
performance-enhancing and exercise recovery benefits.
Exercise-based research with similar functional foods
spurred investigation with tart (e.g. Mortmorency) cherry
concentrate and juice supplementation to help increase
performance by theoretically attenuating muscle damage,
oxidative stress, and inflammation associated with aerobic
challenges [7].
There are a few studies that have evaluated the effects of
tart cherry supplementation on responses to endurancebased exercise. The first endurance-based study investigated the effects of 8-d tart cherry cultivar-blended juice
supplementation on exercise-induced muscle pain surrounding an endurance relay race event (running distance
= 22.5–31.4 km) [27]. Exercise-induced muscle pain was
reduced as a result of tart cherry supplementation, but
the findings were not confirmed by subsequent blood
marker analysis [27]. Following a similar 8-d tart cherry
Page 2 of 23
juice supplementation protocol, a second study reported
greater lower body isometric strength and quicker restoration of muscular function with reduced blood markers of
muscle damage, oxidative stress, and inflammation in response to a marathon run [28]. A third endurance study
examined the effects of 7-d tart cherry concentrate supplementation on physiological markers of muscle damage,
oxidative stress, and inflammation surrounding 3-d of
simulated high-intensity road cycling [4]. Similar to the
second study, reductions of oxidative and inflammatory
responses were the primary findings, thereby demonstrating a potential acute recovery-enhancing effect between
bouts of high-intensity aerobic exercise with tart cherry
supplementation [4].
The primary objective of this study was to determine
whether short-term (10-d) supplementation with a powdered form of tart cherry skins would facilitate greater aerobic performance through attenuation of oxidative stress,
inflammation, muscle damage, and muscle soreness.
Methods
Subjects
Twenty-seven male (n = 18) and female (n = 9) endurancetrained runners or triathletes (21.8 ± 3.9 years, 67.4 ±
11.8 kg, 15.0 ± 6.0 % body fat, 51.2 ± 11.4 kg free fat mass)
participated as subjects in this study. Subjects were recruited through paper and electronically distributed flyers
at Texas A&M University. Entrance criteria required the
runners or triathletes to have been involved in a consistent
running program for at-least 1-year and able to run a halfmarathon (21.1 km) in less than 2 h. Figure 1 provides a
breakdown of the subject population. Subject discontinuation of participation was not related to any aspect of the
supplementation or testing protocol.
All subjects signed informed consent documents and
the study was approved by the Texas A&M University
Institutional Review Board prior to any data collection.
Subjects were not allowed to participate in this study if
they reported any of the following: 1) metabolic disorders
or taking any thyroid, hyperlipidemic, hypoglycemic, antihypertensive, anti-inflammatory (e.g. NSAIDs), and/or androgenic medications; 2) history of hypertension, hepatorenal, musculoskeletal, autoimmune, and/or neurological
disease(s); and 3) allergy to cherries or any cherry components (e.g. polyphenols, anthocyanins, anthocyanidins).
Experimental design
The study was conducted in a randomized, double-blind,
and placebo-controlled manner (see Fig. 2). All subjects
completed a morning familiarization (FAM) session where
they were provided detailed information regarding the
study design, testing procedures, and supplementation
protocols. Informed consent, medical history, and endurance training history questionnaires were also completed
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 3 of 23
Fig. 1 Consort diagram breakdown of the subject population from recruitment to data analysis
during the FAM session. A nurse reviewed medical history
documents and performed a physical exam (resting vital
signs and lung auscultation) on each subject to ensure participation eligibility. A fasting blood sample was taken at
the end of the FAM session. Approximately 10-d prior to
the endurance exercise intervention, subjects returned to
the lab for a morning baseline testing session to determine
body mass, height, and body composition. Following baseline measurements subjects were matched based on average
reported race pace, fat free mass, body mass, and age and
randomly separated into two groups: 1) a placebo group or
2) a powdered tart cherry group. Subjects were instructed
to not change their dietary habits in any way throughout
the study. Nutritional habits were monitored through selfdietary recall for 4-d (3 weekdays and 1 weekend day) of
the first seven supplementation days.
Subjects were instructed to begin supplementation 7-d
prior to the endurance exercise challenge (Day 0). Subjects were asked to fast overnight for 10-h to account
for diurnal variation as well as abstain from exercise and
consumption of non-steroidal anti-inflammatory medications (NSAIDs) for 48-h prior to all testing days. On
the day of the endurance exercise challenge, the subjects
reported to the lab where body mass, resting heart rate,
and resting blood pressure were measured. Subjects then
donated a fasting venous blood sample (approximately
20 ml) using standard clinical procedures and rated perceptions of muscle soreness to a standardized application of
pressure on their dominant thigh at three designed locations using a graphic pain rating scale (GPRS). Twenty minutes prior to the start of the half-marathon race, subjects
were allowed to warm-up as they normally would before
running a road race. Subjects completed a half-marathon
(21.1 km) run outdoors at their normal race/competition
pace. Both water and glucose-electrolyte drinks were provided ad libitum to the subjects at regular intervals during
the race. Fasting (except 60-min post-run) blood samples
and GPRS ratings of quadriceps muscle soreness were
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 4 of 23
Fig. 2 Experimental study design. DEXA dual-energy X-Ray absorptiometer, MVC maximal voluntary contraction, 1-RM 1-repetition maximum, NSAID
non-steroidal anti-inflammatory drugs, GPRS graphic pain rating scale, 7-d 7-day, 48-h 48-hour
completed at 60-min, 24 and 48-h of post-run recovery.
The last or tenth day of supplementation correlated with
48-hours post-run recovery.
Exercise protocol
Half-marathon (21.1 km) run
On the morning of supplementation day 8, all subjects
performed an outdoor half-marathon run (21.1 km) for
best time on a closed course under simulated race day
conditions. Race start (0800) conditions were: ambient
temperature = 22.8 °C, wind = 14.5 kph, humidity = 90 %,
dew point = 21.1 °C. Conditions at the race finish (1030)
were: ambient temperature = 25.0 °C, wind = 14.5 kph,
humidity = 86 %. The race was run completely on concrete and pavement surfaces. All subjects were given 20minutes for individual warm-up routines. At regular
intervals (4 total locations) throughout the race, fluids
(water and/or glucose-electrolyte beverages) were made
available ad libitum to the subjects. Each subject had
their own water and glucose-electrolyte beverage bottle
labeled with a number that corresponded to their race
number. All fluid bottles were weighed before and after
the race to determine fluid consumption for each subject. Official race splits and finish times were recorded
by designated lab staff. Following the race, subjects were
not allowed to run to cool down, only stretching and
minimal ambulation was permitted until the 60-min
post-run testing session.
Supplementation protocol
Subjects were assigned in a double-blinded and randomized manner to ingest a rice flour placebo (P, n = 16) or
powdered tart cherry (TC, n = 11). Subjects were matched
into one of the two groups according to average reported
race pace from previous (within the last 1 year) race
events, fat free mass, body mass, and age. Subjects were
instructed to ingest one 480 mg supplement capsule one
time daily directly after breakfast at 0800 for 7-d prior to,
the day of, and for 2-days following the half-marathon
race for a total supplementation timeline of 10-d. The tart
cherry supplements contained 480 mg of freeze dried
Montmorency tart cherry skin powder derived from tart
cherry skins obtained after juicing (CherryPURE™ Freeze
Dried Tart Cherry Powder, Shoreline Fruit, LLC, Transverse City, MI, USA). Prior analytical testing conducted in
2012 by Advanced Laboratories (Salt Lake City, UT, USA)
demonstrated that 31 mL (10.5 fl oz) of tart cherry juice
provides approximately 600 mg of phenolic compounds
and 40 mg of anthocyanins, which is equivalent to consuming 290 mg of CherryPURE™. Using the same comparison,
the 480 mg CherryPURE™ supplement provided in the
current study would be equivalent to 51.3 mL (17.4 fl oz) of
tart cherry juice providing 991 mg of phenolic compounds
and 66 mg of anthocyanins. The supplements were prepared for distribution by Shoreline Fruit, LLC and sent to
Advanced Laboratories (Salt Lake City, UT, USA) to quantify the nutritional contents of the powdered tart cherry
supplements. Both supplements were prepared in capsules
identical in taste and appearance. The supplements were
packaged in generic bottles by Shoreline Fruit, LLC for
double blind administration.
Procedures
Dietary inventories
Within the first 7-d of supplementation, subjects were
instructed to record all food and fluid intake over a 4-d
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
period (3 weekdays, 1 weekend day). Dietary inventories
were then reviewed by a registered dietician and analyzed
for average daily energy (total kilocalories), macronutrient
(protein, fat, and carbohydrates), and dietary antioxidant
(vitamins C and E, and β-carotene) intake using ESHA
Food Processor (Version 8.6) Nutritional Analysis software
(ESHA Research Inc., Salem, OR, USA).
Anthropometrics and Body composition
At the beginning of every testing session, subjects had
their height and body mass measured according to standard procedures using a Healthometer Professional 500KL
(Pelstar LLC, Alsip, IL, USA) self-calibrating digital scale
with an accuracy of ±0.02 kg. Whole body bone density
and body composition measures (excluding cranium) were
determined with a Hologic Discovery W Dual-Energy Xray Absorptiometer (DEXA; Hologic Inc., Waltham, MA,
USA) equipped with APEX Software (APEX Corporation
Software, Pittsburg, PA, USA) by using procedures previously described [29]. Mean test-retest reliability studies
performed on male athletes in our lab with this DEXA
machine have revealed mean coefficients of variation for
total bone mineral content and total fat free/soft tissue
mass of 0.31–0.45 % with a mean intraclass correlation of
0.985 [30]. On the day of each test, the equipment was calibrated following the manufacturer’s guidelines for quality
assurance.
Muscle soreness perception assessment
Pressure application to the three specified areas of the
quadriceps muscle group on each subject’s dominant leg
was standardized to 50 N of pressure using a handheld
Commander Algometer (JTECH Medical, Salt Lake City,
UT, USA). The standard amount of pressure was applied
to the vastus lateralis at both 25 and 50 % of the distance
between the superior border of the patella to the greater
trochanter of the femur at the hip and to the vastus medalis
at 25 % of the distance between the aforementioned landmarks. These three specific locations were measured and
marked with a permanent marker on each subject during
the baseline muscle soreness perception measurement
before the half-marathon race. The subjects were asked to
maintain these three marked locations between testing
sessions to avoid error with secondary measurement. The
subject was seated in a reclined supine position and given
the algometer GPRS sheet to evaluate the perception of
muscle soreness at each of the three quadriceps locations.
The order of pressure application was standardized across
all sessions and subjects: 25 % VM, 25 % VL, and 50 % VL.
The 50 N of pressure was applied to a relaxed quadriceps
at each of the three locations using the algometer for a
period of 3-sec to give the subject enough time to record
their soreness evaluation on the GPRS. Perceptions of
muscle soreness were recorded by measuring the distance
Page 5 of 23
(centimeters) of the participant mark on the GPRS from
0 cm (no pain). Reliability statistical analyses revealed a
mean intraclass correlation of 0.909.
Blood collection
Subjects donated approximately four teaspoons (20 mL) of
venous blood after a 10-h fast from an antecubital vein
using standard phlebotomy procedures. Blood samples
were collected in two 7.5 mL BD Vacutainer® serum separation tubes (Becton, Dickinson and Company, Franklin
Lakes, NJ, USA), left at room temperature for 15-min, and
then centrifuged at 3500 rpm for 10-min using a standard,
refrigerated (4 °C) bench top Thermo Scientific Heraeus
MegaFuge 40R Centrifuge (Thermo Electron North America
LLC, West Palm Beach, FL, USA). Serum supernatant was
removed and stored at −80 °C in polypropylene microcentrifuge tubes for later analysis. The multiple serum microcentrifuge tubes for each subject was allocated for a specific
group of assays and thawed only once during analysis.
Blood was also collected in a single 3.5 mL BD Vacutainer®
containing K2 EDTA (Becton, Dickinson and Company,
Franklin Lakes, NJ, USA), left at room temperature for 15min, and refrigerated for approximately 3–4 h before
complete blood count analysis.
Clinical chemistry analysis
Whole blood samples were analyzed for complete blood
count with platelet differentials (hemoglobin, hematocrit,
red blood cell counts (RBC), white blood cell counts
(WBC), lymphocytes, granulocytes (GRAN), and mid-range
absolute count (MID) using a Abbott Cell Dyn 1800 (Abbott Laboratories, Abbott Park, IL, USA) automated
hematology analyzer. The internal quality control for
Abbott Cell Dyn 1800 was performed using three levels of
manufacturer control fluids to calibrate acceptable standard
deviation (SD) and coefficients of variation (CV) values for
all aforementioned analytes. Samples were re-run if the
observed values were outside control values and/or clinical
norms according to standard procedures. Reliability statistical analyses revealed a mean intraclass correlation of
0.729 across all measures. Serum samples were analyzed
using a Cobas c111 (Roche Diagnostics GmbH, Indianapolis, IN, USA) automated clinical chemistry analyzer that
was calibrated according to manufacturer guidelines. This
analyzer has been known to be highly valid and reliable in
previously published reports [31]. Each serum sample was
assayed for a standard partial metabolic panel [(aspartate
aminotransferase (AST), alanine aminotransferase (ALT),
and total bilirubin)] and clinical markers of protein and
fatty acid metabolism [(uric acid, creatinine, blood urea
nitrogen (BUN), BUN:creatinine ratio, total protein, and
creatine kinase (CK)]. The internal quality control for the
Cobas c111 was performed using two levels of manufacturer control fluids to calibrate acceptable SD and CV
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
values for all aforementioned assays. Samples were re-run if
the observed values were outside control values and/or
clinical norms according to standard procedures. Reliability
statistical analyses revealed a mean intraclass correlation of
0.793 across all measures.
Markers of anabolic/catabolic hormone status
Serum samples were assayed using standard commercially
available enzyme-linked immunosorbent assay kits (ELISAs) for cortisol and testosterone (ALPCO Diagnostics,
Salem, NH, USA). Serum concentrations were determined
calorimetrically using a BioTek ELX-808 Ultramicroplate
reader (BioTek Instruments Inc., Winooski, VT, USA) at an
optical density of 450 nm against a known standard curve
using manufacturer recommended procedures. Samples
were run in duplicate according to standard procedures.
Test to test variability of performing these assays yielded
average CV values for the aforementioned markers of:
CORT (±6.85 %), and TEST (±4.47 %) with a test retest
correlation for the same markers of: CORT (r = 0.92),
TEST (r = 0.98).
Markers of oxidative stress
Serum samples were assayed using standard commercially
available ELISA kits for Superoxide Dismutase (SOD Activity Assay kit), Total Antioxidant Status (TAS, Antioxidant
Assay kit), Thiobarbituric Acid Reactive Substance (TBARS,
Malondialdehyde-MDA, TCA method kit) (Cayman Chemical Company, Ann Arbor, MI, USA), and Nitrotyrosine
(ALPCO Diagnostics, Salem, NH, USA). Serum concentrations for SOD and Nitrotyrosine were determined calorimetrically using a BioTek ELX-808 Ultramicroplate reader
(BioTek Instruments Inc., Winooski, VT, USA) at an optical
density of 450 nm against a known standard curve using
standard procedures, while TAS serum concentrations were
analyzed calorimetrically at 405 nm. Lastly, serum concentrations for TBARS were determined fluorometrically using
a SpectraMax Gemini multimode plate reader (Molecular
Devices LLC, Sunnyvale, CA, USA) at an excitation wavelength of 530 nm and an emission wavelength of 550 nm
against a known standard curve using standard procedures.
Samples were run in duplicate according to standard procedures. Test to test variability of performing these assays
yielded average CV values for the aforementioned markers
of: SOD (±8.35 %), TAS (±14.24 %), TBARS (±8.30 %),
and NT (±10.03 %) with a test retest correlation for the
same markers of: SOD (r = 0.83), TAS (r = 0.85), TBARS
(r = 0.94), and NT (r = 0.99).
Cytokine/Chemokine markers of inflammation
Serum markers of inflammation [(interleukin-1β (IL-1β),
IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13,
tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and
granulocyte-macrophage colony-stimulating factor (GM-
Page 6 of 23
CSF)] were measured by using a commercially available
Milliplex MAP 13-Plex Human High Sensitivity T-Cell
Magnetic Bead Panel kit (EMD Millipore Corporation, St.
Charles, MO, USA). A minimum of 100 positive beads for
each cytokine/chemokine was acquired with a Luminex
MagPix instrument (Luminex Corporation, Austin, TX,
USA). Samples were run in duplicate according to standard
procedures. Test to test variability of performing these assays yielded an average CV value range of ±4.26 to ±6.05 %
for the aforementioned markers with an average test retest
correlation of r = 0.99 for the same markers.
Statistical analysis
Individual group and time data are presented throughout
as means (± SD), while group effects are presented as
means (± SEM). All related variables were grouped and
analyzed using repeated measures MANOVA in IBM
SPSS Statistics Software version 22.0 for Windows (IBM
Corporation, Armonk, NY, USA). Half-marathon finish
time was also used as a covariate in subsequent ANCOVA
analyses to determine if previously reported statistical outcomes were attributed to running intensity or to supplementation. Post-hoc LSD pairwise comparisons were used
to analyze any significance among groups where needed
with Cohen’s d calculations employed to determine effect
magnitude. Data were considered statistically significant
when the probability of error was less than 0.05 and considered to be trending when the probability of error was
between 0.05 and 0.10.
Results
Subject characteristics
A total of 27 healthy, endurance trained or triathlete men
(n = 18) and women (n = 9) completed the study protocol.
Participant demographic data are presented in Table 1.
One-way ANOVA revealed no significant differences
(p >0.05) in baseline demographic or anthropometric
markers.
Nutritional intake and compliance
Table 2 lists relevant nutrition components analyzed in the
4-d dietary recall. P tended to consume a smaller amount
of average daily calories compared to TC (31.0 kcal/kg vs.
37.4 kcal/kg, p = 0.094). This differential is likely due
dropped subjects (see Fig. 1) causing a greater proportion
of females in P (nf = 3/11, 27.3 %) versus TC (nf = 6/16,
37.5 %). When stratifying the statistical dietary analysis by
gender within each group, average daily calorie (p = 0.44)
and dietary carbohydrate (p = 0.64) consumption was the
same across groups. No other statistically significant interactions were observed across groups with respect to dietary
intake.
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 1 Demographics by study group
Table 2 Relative dietary analysis by study group
Variable
Group
Mean
Group (SEM)
p-value
N
P
16
n/a
n/a
TC
11
n/a
Total
27
n/a
Age
Height (cm)
Body Mass (kg)
Baseline HR (bpm)
2
BMD (g/cm )
FFM (kg)
FM (kg)
Body Fat (%)
Page 7 of 23
P
22.44 ± 4.86
1.214
TC
20.82 ± 1.89
0.569
Total
21.78 ± 3.95
0.761
P
173 ± 11.43
2.851
TC
175 ± 8.59
2.589
Total
174 ± 10.25
1.972
P
65.48 ± 12.07
3.018
TC
70.17 ± 11.25
3.392
Total
67.39 ± 11.76
2.263
P
58.50 ± 9.02
2.255
TC
59.64 ± 4.46
1.343
Total
58.96 ± 58.96
1.426
P
1.04 ± 0.11
0.028
TC
1.08 ± 0.13
0.038
Total
1.06 ± 0.12
0.023
P
48.67 ± 11.32
2.830
TC
54.85 ± 11.01
3.319
Total
51.19 ± 11.41
2.195
P
9.81 ± 3.20
0.801
TC
7.76 ± 2.44
0.735
Total
2.44 ± 3.04
0.585
P
16.87 ± 6.40
1.599
TC
12.31 ± 4.42
1.333
Total
15.01 ± 6.03
1.160
Variable
Group Mean
Average Daily Caloric
Consumption (kcal/kg)
P
0.305
Dietary Protein (g/kg)
0.592
Dietary Carbohydrates
(g/kg)
0.317
Dietary Fat (g/kg)
Dietary Beta-Carotene
(mcg/kg)
0.458
Dietary Vitamin C
[Ascorbic Acid]
(mg/kg)
Dietary Vitamin E
[Alpha-Tocopherol]
(mg/kg)
§
0.085
0.051§
Mean data expressed as means ± SD. Data represents general study population
demographics and anthropometric measures. One-way ANOVA p-levels listed
for each variable: § represents p <0.10 difference between groups. HR heart
rate, BMD bone mineral density, LM lean mass, FFM free-fat mass, FM fat mass
Half-marathon performance measures
Table 3 presents half-marathon split and finish times in
addition to projected versus actual average race paces.
There was no difference in projected race finish times
between groups (p = 0.304). TC subjects had faster halfmarathon split (p = 0.002) and race finish times (p = 0.001)
corresponding to a quicker overall race pace compared to
P. The actual race pace was slower compared to the projected race pace in both groups (p <0.001), but the difference tended to be smaller (p = 0.091) in TC compared to
P. Due to the significant difference in race performance,
half-marathon finish time was used as a covariate in subsequent ANCOVA analyses to determine if other statistical outcomes were attributed to running intensity or to
supplementation.
37.71 ± 11.65
3.51
Total
33.67 ± 10.40
2.00
P
1.29 ± 0.56
0.14
TC
1.62 ± 0.58
0.17
Total
1.42 ± 0.58
0.11
P
3.54 ± 1.50
0.37
TC
4.57 ± 2.00
0.60
Total
3.96 ± 1.76
0.34
P
1.24 ± 0.49
0.12
TC
1.27 ± 0.72
0.22
P
1.25 ± 0.58
0.11
38.01 ± 71.15
17.79
TC
54.22 ± 92.29
27.83
Total
44.62 ± 79.13
15.23
P
0.92 ± 0.69
0.17
TC
1.46 ± 1.78
0.54
1.14 ± 1.25
0.24
0.099 ± 0.095
0.024
Total
0.171
2.19
TC
Total
0.703
30.89 ± 8.75
Group
(SEM)
P
TC
0.106 ± 0.107
0.032
Total
0.102 ± 0.098
0.019
p-value
0.094§
0.146
0.138
0.886
0.611
0.277
0.853
Mean data expressed as means ± SD. Data represents nutritional analysis from
subject 4-d dietary records accounting for subject body mass as a computation
of relative dietary components. One-way ANOVA p-levels listed for each variable:
§ represents p <0.10 difference between groups
Markers of mechanical damage and physiological stress
Table 4 presents the serum mechanical damage and
physiological stress marker data. Serum creatinine and
urea/BUN makers increased on average 19 and 21 %,
respectively, over pre-run values during the recovery in
P, but only 6 and 3 % in TC. Serum total protein content increased on average 4 % over pre-run values during the recovery in P, but decreased 3 % below pre-run
in TC. Significant (or trends approaching significance)
changes across groups and group differences over time
for creatinine (p = 0.047, group p = 0.007), urea/BUN
(p = 0.048, group p = 0.004), and total protein (p =
0.081, group p = 0.060) were further supported by
ANCOVA analyses accounting for running intensity.
Subsequent post-hoc analysis indicated a significantly
attenuated serum creatinine level 60-min post-run and a
mitigated urea/BUN response in TC compared to P 24-h
post-run (see Fig. 3). The total protein response never
increased above pre-run levels over the 48-h recovery in
TC compared to significant elevations 60-min and 48-h
post-run in P (see Fig. 4).
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 3 Running performance by study group
Variable
Group
Mean
½ Marathon Split
Time (min)
P
TC
Total
½ Marathon Finish
Time (min)
½ Marathon Projected
Race Pace (min/km)
½ Marathon Actual
Race Pace (min/km)
Page 8 of 23
Inflammatory response markers
Group (SEM)
p-value
54.30 ± 4.18
1.045
0.002*
49.03 ± 3.65
1.099
52.15 ± 4.71
0.906
P
118 ± 9.72
2.429
TC
103 ± 9.28
2.798
Total
112 ± 11.86
2.283
P
12.00 ± 1.28
0.338
TC
11.45 ± 1.45
0.407
Total
11.77 ± 1.35
0.264
P
14.48 ± 1.19
0.293
TC
12.70 ± 1.14
0.354
Total
13.76 ± 1.45
0.230
0.001*
0.304
0.002*
Mean data expressed as means ± SD. Data represents the half-marathon performance measures. Half-marathon projected race pace figures were calculated based
upon subjects’ self-reported previous endurance running race performances.
The overall MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and
group x time (p = 0.091). Univariate ANOVA p-levels from the MANOVA analysis
are presented for both pacing variables. One-way ANOVA p-levels listed for each
timing variable: * represents p <0.05 difference between groups
Anabolic/catabolic hormone response markers
Table 5 demonstrates the serum testosterone and cortisol hormone marker response. Testosterone and cortisol demonstrated significant changes over time and
from baseline, peaking (elevated or depressed) 60-min
post-run. Significant group differences over time and
from pre-run levels were reported for serum cortisol (p
= 0.012, delta p = 0.016). Serum cortisol levels 60-min
post-run increased 44 % over pre-run values in P, but
only 15 % in TC. Subsequent post-hoc analysis indicated significantly attenuated serum cortisol levels in
TC compared to P 60-min and 24-h post-run (see
Fig. 4). These results were supported when accounting
for differences in running intensity.
Markers of free radical production and oxidative stress
Table 6 shows the response of free radical production
and oxidative stress markers. None of the measures for
free radical production or oxidative stress demonstrated
significant changes over time. Serum TAS levels tended
to be different between groups over time (p = 0.089),
which was supported when accounting for running intensity differences. Serum TAS levels decreased 1–8 %
from pre-run levels in P over the 48-h recovery, but
increased 15–31 % in TC (p = 0.046). Post-hoc analysis
revealed a linear increase in TC serum TAS activity
from pre-run levels that was statistically different from
P and pre-run values at 48-h of recovery (see Fig. 5).
Table 7 shows the serum inflammatory cytokine and chemokine marker response. Accounting for running intensity differences, both IL-2 (p = 0.089) and IL-6 (p = 0.064)
measures tended to be different between groups over time.
Serum IL-2 levels increased 0.2 % from pre-run levels
throughout recovery in P, but decreased 28 % in TC.
Further, serum IL-6 levels increased 64 % from pre-run in
P, but only 17 % in TC. Delta post-hoc analyses demonstrated significant attenuation of serum IL-6 measures 60min post-run in TC compared to P (104 % TC increase vs.
210 % P increase). Serum IL-2 significantly decreased in
TC compared to P and pre-run measures over the 48-h
recovery (see Fig. 6).
Anti-inflammatory response markers
Table 8 presents the serum anti-inflammatory cytokine
marker results. Accounting for running intensity, serum
IL-13 levels were significantly different across groups (p =
0.031) and tended to be different between groups over
time (p = 0.053). Serum IL-13 markers decreased 6 % on
average from pre-run over the 48-h recovery in P, compared to a 13 % decrease in TC. Specifically, at 60-min
post-run, serum IL-13 markers increased 5 % over pre-run
values in P, but actually decreased 7 % below pre-run in
TC. The serum IL-13 group (p = 0.029) and group by time
(p = 0.014) differences from pre-run levels over the recovery period were also significant (see Fig. 6).
Clinical markers of immune-related complete blood
counts
Table 9 demonstrates the immune response-related
complete blood count marker results. All immune-related
complete blood counts demonstrated significant changes
over time (p <0.001), but no significant changes between
groups.
Muscle soreness perception assessment
Table 10 presents perceptions of muscle soreness. Perceptions were not measured at baseline. All locations of muscle
soreness measurement demonstrated significant changes
over time (p <0.001), peaking 60-min post-run. Significant
differences between groups over time were found in vastus
medalis (¼) soreness perception (p = 0.035) that was confirmed when accounting for running intensity discrepancies. Subsequent post-hoc analysis indicated significantly
attenuated (34 %) pre-run vastus medalis (¼) soreness in
TC compared to P with no differences in soreness perception between groups over the recovery (see Fig. 7).
The change from pre-run vastus medalis (¼) soreness
was smaller in P soreness perception compared to TC
(p = 0.035) over the 48-h recovery. The other two locations of quadriceps soreness perception testing did not
Variable
Group
Baseline
Pre-Run
AST (U/L)
P
32.69 ± 33.67
26.62 ± 14.97
TC
29.46 ± 10.54
26.30 ± 7.48
ALT (U/L)
Total Billirubin (umol/L)
Urea/BUN (mmol/L)
Creatinine (umol/L)
Uric Acid (umol/L)
CK (U/L)
Total Protein (mmol/L)
24-hr Post
48-hr Post
Group Mean
p-value (GG)
37.20 ± 17.36
50.52 ± 22.96
43.33 ± 16.68
38.07 ± 3.98
G = 0.911
36.96 ± 9.68
49.97 ± 31.12
44.14 ± 24.60
37.37 ± 4.80
T = 0.002*
TL = 0.005*
Tq = 0.593
G X T = 0.859
G X Tq = 0.740
G X TL = 0.707
†Ψ
†Ψ◊
†Ψ#
p-value (WSC)
RFT Covariate
p-value (WSC)
G = 0.402
Time Mean
31.08 ± 5.27
26.46 ± 2.45
37.08 ± 2.89
50.25 ± 5.20
43.74 ± 3.96
P
22.09 ± 13.55
20.32 ± 7.15
23.65 ± 8.04
26.42 ± 7.36
28.53 ± 8.02
24.20 ± 2.15
G = 0.576
TC
23.06 ± 8.22
23.13 ± 10.39
27.94 ± 14.22
30.07 ± 14.80
26.11 ± 2.59
T = 0.008*
TL = 0.006*
Tq = 0.677
Time Mean
22.57 ± 2.29
21.73 ± 1.68
25.01 ± 1.76Ψ
27.18 ± 2.09Ψ◊
29.30 ± 2.20†Ψ◊#
G X T = 0.842
G X Tq = 0.603
G X TL = 0.869
P
9.01 ± 2.87
8.15 ± 3.03
13.03 ± 4.68
8.44 ± 4.06
7.65 ± 3.45
9.25 ± 0.76
G = 0.756
TC
8.71 ± 4.64
7.60 ± 3.75
11.65 ± 4.50
8.99 ± 4.22
7.46 ± 2.75
8.88 ± 0.91
T <0.001*
Tq = 0.001*
G X T = 0.699
G X TL = 0.694
AM ± 10.22
†Ψ
◊
◊
Time Mean
8.86 ± 0.72
7.88 ± 0.65
12.34 ± 0.90
8.71 ± 0.81
7.55 ± 0.62
P
4.75 ± 1.08
5.45 ± 1.36
6.36 ± 1.14
7.13 ± 1.15
6.33 ± 1.44
6.00 ± 0.21
TC
5.11 ± 0.69
6.02 ± 1.17
6.16 ± 1.01
6.40 ± 1.44
6.03 ± 1.58
5.94 ± 0.26
Time Mean
4.93 ± 0.19
5.74 ± 0.25†
6.26 ± 0.21†Ψ
6.77 ± 0.25†Ψ
6.18 ± 0.29†#
71.71 ± 15.07
74.29 ± 11.54
106.56 ± 15.45†Ψ
79.85 ± 10.88†◊
78.20 ± 11.17†
82.12 ± 3.12
G = 0.651
80.34 ± 12.72
84.36 ± 3.77
T <0.001*
P
TC
BUN/Creatinine
Ratio
60-min Post
77.20 ± 15.93
82.29 ± 13.96
†Ψ
100.44 ± 25.52
†Ψ
◊
81.54 ± 15.08
†◊
◊
G = 0.057§
G = 0.614
Tq = 0.484
G = 0.857
G X Tq = 0.591
G = 0.426
T <0.001*
TL <0.001*
TL = 0.026*
G X T = 0.144
G X TL = 0.095§
G X TL = 0.014*
G = 0.522
TL = 0.007*
Tq <0.001*
§
Time Mean
74.45 ± 3.02
78.29 ± 2.46
103.50 ± 3.94
80.70 ± 2.49
79.27 ± 2.31
P
16.60 ± 3.05
18.58 ± 5.58
15.22 ± 4.38
22.49 ± 4.61
20.36 ± 5.29
18.65 ± 0.90
G = 0.589
TC
16.97 ± 3.87
18.33 ± 3.50
15.80 ± 3.53
19.50 ± 3.61
18.79 ± 5.26
17.88 ± 1.09
T <0.001*
TL = 0.001*
Tq = 0.240
Time Mean
16.75 ± 3.34
18.48 ± 4.77
15.46 ± 3.99Ψ
21.27 ± 4.41†Ψ◊
19.72 ± 5.23†◊#
G X T = 0.158
G X TL = 0.140
G X TL = 0.103§
P
271 ± 46
292 ± 44
373 ± 48
321 ± 48
308 ± 47
313 ± 11
G = 0.789
TC
290 ± 50
308 ± 52
364 ± 64
326 ± 82
302 ± 65
318 ± 14
T <0.001*
Tq <0.001*
TL = 0.014*
G X T = 0.444
G X TL = 0.188
G X TL = 0.015*
†
†Ψ
†Ψ◊
G X T = 0.087
†◊#
Time Mean
280 ± 9
300 ± 9
369 ± 11
324 ± 13
305 ± 11
P
606 ± 1696
276 ± 510
532 ± 627
907 ± 683
593 ± 525
583 ± 144
472 ± 173
TC
298 ± 317
228 ± 191
474 ± 253
870 ± 771
490 ± 395
Time Mean
452 ± 260
252 ± 81
503 ± 100Ψ
889 ± 141Ψ◊
541 ± 93Ψ#
67.51 ± 8.56
72.93 ± 5.41†
76.78 ± 4.95†
70.77 ± 5.35◊
†
†
◊
P
TC
Time Mean
68.70 ± 8.06
68.11 ± 1.64
76.28 ± 4.78
†
74.61 ± 1.01
74.94 ± 8.85
†
75.86 ± 1.33
67.83 ± 4.52
Ψ◊
69.30 ± 0.99
G = 0.724
G = 0.806
T = 0.036*
TL = 0.139
Tq = 0.836
G X T = 0.680
G X Tq = 0.416
G X Tq = 0.599
73.64 ± 0.87
G = 0.746
78.20 ± 6.84†#
73.19 ± 1.05
T < 0.001*
79.20 ± 1.30
G X TL = 0.010*
G = 0.329
G = 0.626
80.21 ± 6.48†Ψ#
†Ψ◊#
G X TL = 0.246
G X T = 0.316
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 4 Markers of muscle catabolism, Secondary muscle damage, and Physiological stress
G = 0.846
TL = 0.008*
TL <0.001*
§
G X TL = 0.066
G X TL = 0.004*
Page 9 of 23
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the response to muscle catabolism, mechanical damage, and physiological stress at each
testing session during the 10 day intervention. MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.504). Univariate ANOVA p-levels from MANOVA analysis are presented for each
variable. Univariate ANOVA p-levels are listed first by the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time or group x time interaction
with significance indicated by the following super/subscripts: *indicates p <0.05 p-level significance, §indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: † represents
p <0.05 difference from baseline value, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post. AST aspartate aminotransferase,
ALT alanine aminotransferase, BUN blood urea nitrogen, CK creatine kinase, RFT race finish time, G group p-level, T time p-level, G x T interaction, q quadratic p-level, L linear p-level
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 10 of 23
Fig. 3 Secondary indices of muscle damage and protein catabolism. Data expressed as means ± SE and significance indicated by the following super/
subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts:
^ represents p <0.05 difference between groups, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post,
# represents p <0.05 difference from 24-hr post
reveal any significant differences between supplementation groups.
Discussion
Previous research has investigated the efficacy of tart
cherry supplementation surrounding bouts of endurance
exercise, however, this is the first study to investigate the
effect of Montmorency tart cherry skin powder on acute
endurance performance recovery. It was hypothesized that
supplementation with this novel powdered tart cherry skin
supplement prior to a single bout of endurance exercise
would attenuate markers of muscle damage, oxidative
stress, inflammation, and perceptions of muscle soreness
in facilitation of faster recovery. Tart cherry ingestion
reduced post-run serum markers of muscle catabolism,
secondary muscle damage, and physiological stress over
the 48-h recovery period compared to the placebo. Decreased muscle catabolism and stress are indicative of the
attenuated recovery inflammatory response reported with
tart cherry supplementation versus placebo. Antioxidant
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 11 of 23
Fig. 4 Markers of protein catabolism and physiological stress. Data expressed as means ± SE and significance indicated by the following super/
subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following
superscripts: ^ represents p <0.05 difference between groups, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from
60-min post, # represents p <0.05 difference from 24-hr post
activity in those who ingested tart cherry was greater than
the placebo, particularly 24 and 48-h post-run. Despite
increases in actual over projected race pace times in both
groups, the tart cherry group demonstrated smaller pace
differences compared to placebo. Medial quadriceps soreness in tart cherry supplementers was significantly lower
pre-run compared to those ingesting the placebo. However, results indicated a smaller change from pre-run medial quadriceps soreness in placebo supplementers over the
48-h recovery period compared to the tart cherry group.
Examining subject endurance performance, the increase
in actual versus projected race pace irrespective of group is
likely attributed to the 10-h fast and blood draw on the day
of the endurance exercise challenge that would have not
been experienced prior to any other race. The apparent
beneficial effect of tart cherry powder supplementation on
endurance performance through a decrease in race completion time is consistent with some of the previously published findings. Nieman et al. conducted a study in young,
healthy males with 2-wk of quercetin supplementation
(1000 mg/day) versus placebo [32]. Following a 12-min
treadmill running trial at a 15 % grade and self-selected
speed, Nieman et al. reported a significantly greater pre-
supplementation versus post-supplementation change in
distance covered with quercetin supplementation versus
placebo [32]. The polyphenol content of a fruit-derived
supplement similar to tart cherry was proven beneficial
after extended supplementation in a study conducted by
Kang et al. on regular endurance exercisers [33]. Kang et al.
demonstrated that 30-d supplementation of oligomerized
lychee fruit extract significantly elevated both submaximal
running time and anaerobic threshold compared to a vitamin C/E mixture and a placebo [33].
Attenuation of muscle catabolism and secondary markers
of muscle damage following prolonged endurance exercise
physiologically provides the body optimal conditions for
quicker recovery in preparation for subsequent performance bouts. Studying trained endurance runners, Kratz
et al. [34] analyzed hemodynamic clinical chemistry makers
before, 4 and 24-h post-Boston marathon. The results of
demonstrated significant increases in total CK, AST, ALT,
total protein, uric acid, total bilirubin, BUN, and creatinine
4-h post-race and confirmed significant elevations in CK,
BUN, creatinine, uric acid, ALT, and AST over pre-race
values 24-h post-race [34]. Bell et al. [35], in an acute
endurance study following a combination of cycling sprints
Variable
Group
Baseline
Pre-Run
60-min Post
24-hr Post
48-hr Post
Group Mean
p-value (GG)
Cortisol
(ug/dL)
P
20.92 ± 7.21
24.04 ± 5.16
34.63 ± 10.14^†Ψ
19.17 ± 4.87Ψ◊
21.14 ± 5.83◊
23.98 ± 1.23
G = 0.408
22.36 ± 1.48
T <0.001*
Tq <0.001*
TL = 0.259
G X T = 0.005*
G X Tq = 0.012*
G X Tq = 0.030*
Testosterone (ng/mL)
Test/Cort Ratio
◊
p-value (WSC)
RFT Covariate
p-value (WSC)
G = 0.868
TC
21.34 ± 6.68
22.14 ± 7.35
25.48 ± 7.45
20.36 ± 5.93
22.50 ± 4.77
Time Mean
21.13 ± 1.37
23.09 ± 1.20
30.06 ± 1.80†Ψ
19.76 ± 1.04Ψ◊
21.82 ± 1.06◊#
P
7.22 ± 3.90
6.77 ± 3.55
6.34 ± 3.55
6.48 ± 3.32
6.74 ± 3.41
6.71 ± 0.88
G = 0.745
TC
6.65 ± 4.24
6.52 ± 3.89
5.59 ± 3.48
6.21 ± 3.75
6.31 ± 3.69
6.26 ± 1.06
T = 0.058§
Tq = 0.042*
Tq = 0.026*
Time Mean
6.94 ± 0.79
6.64 ± 0.72
5.96 ± 0.69†Ψ
G X T = 0.848
G X TL = 0.881
G X TL = 0.171
0.037 ± 0.026
0.030 ± 0.018
P
0.019 ± 0.010
6.34 ± 0.69
6.53 ± 0.69
0.035 ± 0.024
0.034 ± 0.020
0.031 ± 0.005
0.032 ± 0.006
TC
0.035 ± 0.023
0.035 ± 0.023
0.026 ± 0.023
0.034 ± 0.024
0.030 ± 0.021
Time Mean
0.036 ± 0.024
0.032 ± 0.020
0.022 ± 0.016†Ψ
0.035 ± 0.023◊
0.032 ± 0.020◊
G = 0.497
G = 0.874
G = 0.546
T = 0.001*
Tq = 0.009*
Tq = 0.588
G X T = 0.327
G X Tq = 0.101§
G X Tq = 0.290
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 5 Anabolic/Catabolic hormone response
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the stress and sex hormone response at each testing session during the 10 day intervention.
MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.102). Univariate ANOVA p-levels from MANOVA analysis are presented for each variable. Univariate ANOVA p-levels are listed first by
the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time or group x time interaction with significance indicated by the following super/subscripts:
* indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents p <0.05 difference between groups, † represents p <0.05 difference
from baseline value, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post. Cort/Test Cortisol/Testosterone ratio, RFT race finish time, G
group p-level, T time p-level, G x T interaction, q quadratic p-level, L linear p-level
Page 12 of 23
Variable
Group
Baseline
Pre-Run
Nitrotyrosine (nM)
P
279 ± 305
TC
305 ± 425
TBARS (uM)
TAS (mM)
SOD (U/mL)
60-min Post
24-hr Post
48-hr Post
Group Mean
p-value (GG)
214 ± 164
231 ± 180
193 ± 139
198 ± 156
223 ± 71
G = 0.493
284 ± 382
319 ± 436
260 ± 352
302 ± 435
294 ± 85
T = 0.177
TL = 0.183
Tq = 0.667
G X T = 0.699
G X TL = 0.619
G X TL = 0.597
Ψ
Ψ◊
◊
Time Mean
292 ± 70
249 ± 53
275 ± 60
227 ± 48
250 ± 58
P
8.24 ± 4.62
7.59 ± 2.54
7.01 ± 4.24
7.35 ± 3.52
7.73 ± 3.39
7.59 ± 0.71
8.38 ± 0.86
p-value (WSC)
RFT Covariate
p-value (WSC)
G = 0.852
G = 0.484
G = 0.840
TC
8.34 ± 4.06
7.94 ± 4.08
7.91 ± 3.46
8.93 ± 4.52
8.79 ± 4.09
Time Mean
8.29 ± 0.86
7.77 ± 0.64
7.46 ± 0.77
8.14 ± 0.77
8.26 ± 0.72
T = 0.690
Tq = 0.332
Tq = 0.462
G X T = 0.783
G X TL = 0.547
G X TL = 0.520
P
3.13 ± 0.85
3.20 ± 0.88^
3.08 ± 0.89
3.18 ± 1.08
2.96 ± 0.95
3.11 ± 0.17
G = 0.476
TC
2.99 ± 0.84
2.50 ± 0.97
2.87 ± 1.07
2.96 ± 1.26
3.27 ± 0.87Ψ
2.92 ± 0.20
T = 0.713
Tq = 0.321
TL = 0.436
Time Mean
3.06 ± 0.17
2.85 ± 0.18
2.98 ± 0.19
3.07 ± 0.23
3.12 ± 0.18
G X T = 0.239
G X Tq = 0.089§
G X Tq = 0.089§
P
0.49 ± 0.09
0.52 ± 0.11
0.50 ± 0.12
0.49 ± 0.08
0.49 ± 0.14
0.50 ± 0.02
G = 0.198
TC
0.45 ± 0.10
0.46 ± 0.16
0.47 ± 0.15
0.42 ± 0.15
0.48 ± 0.10
0.46 ± 0.02
T = 0.687
TL = 0.756
TL = 0.155
Time Mean
0.47 ± 0.02
0.49 ± 0.03
0.49 ± 0.03
0.46 ± 0.02
0.48 ± 0.03
G X T = 0.808
G X TL = 0.564
G X TL = 0.656
G = 0.381
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 6 Markers of free radical production and oxidative stress
G = 0.285
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the response to reactive oxygen and nitrogen species production in addition to
antioxidant activity at each testing session during the 10 day intervention. MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.684). Univariate ANOVA p-levels from MANOVA analysis are presented for each variable. Univariate ANOVA p-levels are listed first by the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time
or group x time interaction with significance indicated by the following super/subscripts: § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents p <0.05
difference between groups, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post. TBARS thiobarbituric acid reactive substances, TAS total antioxidant status, SOD superoxide
dismutase, RFT race finish time, G group p-level, T time p-level, G x T interaction, q quadratic p-level, L linear p-level
Page 13 of 23
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 14 of 23
Fig. 5 Changes in antioxidant activity with supplementation and endurance exercise. Data expressed as means ± SE and significance indicated by
the following super/subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated
by the following superscripts: ^ represents p <0.05 difference between groups, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05
difference from 60-min post, # represents p <0.05 difference from 24-hr post
and time trials, reported results similar to the current study,
demonstrating no differences in the CK response between
Montmorency tart cherry concentrate and placebo supplementation. Unlike the current study, Howatson et al. [28]
following marathon running demonstrated a trend of lower
post-run CK levels when supplementing with tart cherry
juice compared to placebo up to 48-h of recovery. Despite
conflicting evidence among previous endurance-based tart
cherry research, the post-run collective attenuation of these
markers in the current study demonstrates a beneficial
effect of powdered tart cherry supplementation on indices
of muscle catabolism.
Previous research in the literature seems to conclude
that the inflammatory process is mediated by both proinflammatory cytokines [36] and neuroendocrinological
factors [37]. However, it has also been demonstrated that
as major players in the development of secondary muscle
damage, neutrophils, may also amplify the release of inflammatory cytokines [38, 39]. Nieman et al. [40] supplemented trained cyclists with quercetin, quercetin-EGCG
(epigallocatechin 3-gallate), or placebo soft chews for 24-d
surrounding 3-d of consecutive bouts of 3-h submaximal
cycling. Nieman et al. [40] reported a significant decreases
in plasma concentrations IL-6 immediately post-exercise
on the third exercise day in the quercetin-EGCG group
compared to placebo [40]. Howatson et al. [28] reported
significantly lower inflammation immediately postmarathon through analysis of IL-6 that coincided with
quicker recovery of knee extensor maximal strength following the marathon in Montmorency tart cherry juice
supplemented subjects compared to placebo. Coinciding
with the reduced inflammatory findings of Nieman et
al. [40] and Howatson et al. [28] following endurance
challenges, the current half-marathon study also reported a post-run attenuation in IL-6 with powdered
tart cherry supplementation versus placebo. Similar to
the post-exercise reduction in anti-inflammatory response (IL-10) in the quercetin-EGCG group published
by Nieman et al. [40], the powdered tart cherry group
in the current study also demonstrated similar changes
via an attenuated IL-13 response over the 48-h recovery
compared to placebo.
Glucocorticoids, specifically cortisol, released due to activation of the stress response through muscle mechanical
microtrauma and ROS production have demonstrated an
immunosuppressive influence. Davison and Gleeson [41],
in an investigation of moderately trained males during
2.5-h moderate intensity cycling compared the effects of a
beverage containing a vitamin C supplement with and
without carbohydrate before and during endurance exercise. This study by Davison and Gleeson [41] revealed a
significant increase in plasma cortisol levels immediately
and 1-h post-exercise in both the placebo and vitamin C
only supplemented groups with no significant difference
between these two groups at 1-h post-exercise [41]. The
addition of carbohydrates (alone or with vitamin C)
significantly lowered the cortisol response during the exercise recovery up to 1-h post-exercise [41]. This result
potentially demonstrates lower physiological stress postexercise due to a higher energy state. The results of the
current study revealed a similar cortisol response 60-min
and 24-h post-run as both fasted groups demonstrated an
increase from pre-run values, but the placebo group
response from pre-run was significantly greater than the
tart cherry group. This cortisol response group difference
60-min post-run may be due to a combination of antiinflammatory and antioxidant effects of tart cherry
anthocyanins.
Due to the reduced cortisol response 60-min post-run
following tart cherry supplementation in the current study,
Variable
Group
TNF-α (pg/mL)
P
2.34 ± 1.23
2.74 ± 1.22
3.02 ± 1.55
2.48 ± 1.04
TC
2.49 ± 0.98
2.82 ± 0.90
2.93 ± 1.36
Time Mean
2.40 ± 1.12
2.77 ± 1.08†
2.98 ± 1.45†
IFN-γ (pg/mL)
IL-1β (pg/mL)
IL-2 (pg/mL)
IL-8 (pg/mL)
IL-12p70
(pg/mL)
Pre-Run
60-min Post
24-hr Post
48-hr Post
Group Mean
p-value (GG)
p-value (WSC)
RFT Covariate
p-value (WSC)
2.49 ± 0.90
2.61 ± 0.26
G = 0.922
2.60 ± 0.91
2.42 ± 0.82
2.65 ± 0.31
T = 0.003*
Tq = 0.003*
TL = 0.156
2.53 ± 0.97Ψ◊
2.46 ± 0.85Ψ◊
G X T = 0.779
G X TL = 0.504
G X TL = 0.151
G = 0.654
P
7.67 ± 6.52
8.02 ± 7.77
8.73 ± 9.49
7.36 ± 7.15
7.75 ± 7.78
7.91 ± 2.55
G = 0.382
TC
10.96 ± 11.44
10.71 ± 9.14
11.51 ± 12.50
12.47 ± 17.61
11.68 ± 15.42
11.47 ± 3.08
T = 0.604
Tq = 0.184
TL = 0.424
Time Mean
9.01 ± 8.81
9.12 ± 8.29
9.86 ± 10.67
9.44 ± 12.46
9.35 ± 11.41
G X T = 0.388
G X TL = 0.456
G X Tq = 0.461
P
0.67 ± 0.15
0.85 ± 0.21
0.84 ± 0.19
0.75 ± 0.20
0.69 ± 0.16
0.76 ± 0.08
G = 0.059§
TC
0.93 ± 0.51
1.12 ± 0.58
1.05 ± 0.39
0.98 ± 0.44
0.93 ± 0.40
1.00 ± 0.09
T <0.001*
Tq <0.001*
TL = 0.559
Time Mean
0.78 ± 0.36
0.96 ± 0.42†
0.92 ± 0.30†
0.85 ± 0.33Ψ◊
0.79 ± 0.30Ψ◊
G X T = 0.860
G X Tq = 0.662
G X TL = 0.465
G = 0.570
G = 0.058§
P
1.18 ± 0.96
1.33 ± 1.10
1.51 ± 1.38
1.23 ± 0.85
1.27 ± 0.94
1.30 ± 0.28
G = 0.939
TC
1.17 ± 1.20
1.64 ± 2.18
1.32 ± 0.99
1.12 ± 1.01
1.11 ± 1.06
1.27 ± 0.34
T = 0.070§
Tq = 0.001*
TL = 0.293
G X T = 0.290
G X TL = 0.195
G X TL = 0.089§
Time Mean
IL-6 (pg/mL)
Baseline
P
1.17 ± 1.04
0.63 ± 0.54^
†
1.46 ± 1.60
0.75 ± 0.53^
†
†
1.43 ± 1.22
†Ψ
2.33 ± 1.38
†Ψ
◊
◊
1.18 ± 0.90
0.69 ± 0.44^
1.21 ± 0.97
◊
Ψ◊
0.68 ± 0.43
Ψ
TC
0.94 ± 1.00
1.14 ± 1.27
2.32 ± 1.69
0.89 ± 0.97
0.79 ± 0.76
Time Mean
0.76 ± 0.76
0.91 ± 0.90†
2.33 ± 1.48†Ψ
0.77 ± 0.69Ψ◊
0.72 ± 0.58Ψ◊
G = 0.786
1.02 ± 0.19
G = 0.017*
G = 0.509
1.21 ± 0.23
T <0.001*
Tq <0.001*
Tq = 0.648
G X T = 0.550
G X TL = 0.053§
G X TL = 0.064§
P
2.74 ± 1.58
2.84 ± 1.29
6.21 ± 3.51
2.94 ± 1.24
2.52 ± 1.01
3.45 ± 0.4
G = 0.002*
TC
3.31 ± 1.87
3.24 ± 1.71
5.39 ± 2.78
3.26 ± 2.08
2.74 ± 1.47
3.59 ± 0.49
T <0.001*
Tq <0.001*
Tq = 0.185
G X T = 0.287
G X Tq = 0.269
G X Tq = 0.166
†
◊
Ψ◊#
Time Mean
2.98 ± 1.69
3.00 ± 1.46
5.88 ± 3.20
3.07 ± 1.61
2.61 ± 1.20
P
1.79 ± 1.83
1.84 ± 1.75
1.95 ± 1.93
1.70 ± 1.56
1.81 ± 1.93
1.82 ± 0.42
TC
1.54 ± 1.78
1.59 ± 1.52
1.75 ± 1.93
1.34 ± 1.29
1.27 ± 1.12
1.50 ± 0.51
Time Mean
1.69 ± 1.78
1.74 ± 1.63
1.87 ± 1.89†
1.55 ± 1.44Ψ◊
1.59 ± 1.65Ψ◊
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 7 Pro-inflammatory cytokines and chemokines
G = 0.637
G = 0.009*
G = 0.706
T = 0.012*
Tq = 0.008*
Tq = 0.893
G X T = 0.310
G X Tq = 0.124
G X Tq = 0.167
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the pro-inflammatory response at each testing session during the 10 day intervention.
MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.302). Univariate ANOVA p-levels from MANOVA analysis are presented for each variable. Univariate ANOVA p-levels are listed
first by the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time or group x time interaction with significance indicated by the following
super/subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents p <0.05 difference between groups, †
represents p <0.05 difference from baseline value, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post. TNF-α tumor necrosis
factor alpha, IFN-γ interferon gamma, IL interleukin, RFT race finish time, G group p-level, T time p-level, G x T interaction, q quadratic p-level, L linear p-level
Page 15 of 23
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 16 of 23
Fig. 6 Influence of supplementation and endurance exercise on markers of the inflammatory and anti-inflammatory response. Data expressed
as means ± SE and significance indicated by the following super/subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level
significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents p <0.05 difference between groups, Ψ represents
p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post
it is likely that this anthocyanin-rich supplementation may
modulate endogenous cytokine secretion following stressful
exercise challenges. An acute supplementation study providing moderately active subjects with 48 g of anthocyaninrich black currant extract immediately surrounding a single
bout of high-intensity rowing conducted by Lyall et al. [42]
demonstrated a significant post-exercise attenuation of proinflammatory cytokine production from LPS-stimulated
cells. Lyall et al. [42] postulated from subsequent in vitro
experimentation that this reduced cytokine production may
have resulted from anthocyanin-based inhibition of NF-κBmediated mechanisms. In the current study, attenuated IL6 and serum cortisol levels during post-run recovery in tart
cherry supplementers compared to placebo, demonstrates a
potential relationship between the perception of physiological stress, regulation of anti-inflammatory cytokines,
and cortisol release through NF-κB-mediation.
The attenuation muscle catabolic indices in the current
study may also be partially attributed to an improved
post-run redox balance with tart cherry supplementation
Variable
IL-4 (pg/mL)
IL-5 (pg/mL)
IL-7 (pg/mL)
IL-10 (pg/mL)
IL-13 (pg/mL)
Group
Baseline
Pre-Run
60-min Post
24-hr Post
48-hr Post
Group Mean
p-value (GG)
p-value (WSC)
RFT Covariate
p-value (WSC)
P
4.57 ± 2.02
5.51 ± 2.31
5.20 ± 2.15
4.02 ± 1.49
4.21 ± 1.63
4.70 ± 1.28
G = 0.304
TC
6.93 ± 8.98
8.71 ± 11.72
6.65 ± 6.37
5.41 ± 5.13
6.38 ± 7.03
6.82 ± 1.55
T = 0.012*
Tq = 0.012*
TL = 0.309
G X T = 0.320
G X Tq = 0.189
G X TL = 0.189
Ψ◊
Ψ◊#
Time Mean
5.53 ± 5.89
6.82 ± 7.64
5.79 ± 4.34
4.59 ± 3.45
5.09 ± 4.66
P
0.57 ± 0.37
0.63 ± 0.42
0.66 ± 0.47
0.66 ± 0.46
0.61 ± 0.40
TC
0.96 ± 0.75
1.01 ± 0.73
1.07 ± 0.76
1.01 ± 0.80
0.87 ± 0.59
Time Mean
0.73 ± 0.58
0.78 ± 0.59
0.82 ± 0.62
0.80 ± 0.63
0.71 ± 0.49Ψ◊#
0.62 ± 0.14
G = 0.102§
0.98 ± 0.16
§
T = 0.093
G X T = 0.542
G = 0.165
G = 0.013*
Tq = 0.013*
Tq = 0.452
G X TL = 0.185
G X TL = 0.205
P
3.75 ± 1.63
3.37 ± 1.57
4.66 ± 2.61
3.72 ± 1.81
3.47 ± 1.15
3.80 ± 0.43
G = 0.295
TC
4.66 ± 2.54
4.27 ± 1.84
5.12 ± 2.22
4.55 ± 1.69
4.01 ± 1.42
4.52 ± 0.52
T <0.001*
Tq = 0.010*
TL = 0.845
G X T = 0.708
G X TL = 0.492
G X TL = 0.485
†
†Ψ
◊
◊#
Time Mean
4.12 ± 2.06
3.74 ± 1.71
4.85 ± 2.42
4.06 ± 1.78
3.69 ± 1.27
P
2.91 ± 3.13
2.77 ± 1.89
24.17 ± 26.99
2.77 ± 1.78
2.68 ± 1.68
7.06 ± 1.36
TC
3.31 ± 2.74
3.99 ± 5.07
17.16 ± 18.60
3.66 ± 3.69
2.79 ± 1.98
6.18 ± 1.64
Time Mean
3.07 ± 2.93
3.27 ± 3.51
21.31 ± 23.79†Ψ
3.13 ± 2.70◊
2.72 ± 1.77◊
P
1.52 ± 0.95
1.77 ± 1.14
1.86 ± 1.27
1.55 ± 1.00
1.58 ± 0.86
1.65 ± 0.36
G = 0.091§
TC
2.56 ± 2.01
2.96 ± 2.37
2.74 ± 1.75
2.56 ± 2.00
2.40 ± 1.66
2.65 ± 0.43
Time Mean
1.94 ± 1.53
2.25 ± 1.80†
2.22 ± 1.52†
1.96 ± 1.54Ψ◊
1.91 ± 1.29Ψ◊
G = 0.427
G = 0.683
G = 0.948
T = 0.001*
Tq = 0.001*
Tq = 0.691
G X T = 0.421
G X Tq = 0.495
G X TL = 0.509
T = 0.006*
Tq = 0.003*
Tq = 0.027*
G X T = 0.538
G X TL = 0.236
G X Tq = 0.053§
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 8 Anti-inflammatory cytokines
G = 0.031*
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the anti-inflammatory response at each testing session during the 10 day intervention.
MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.447). Univariate ANOVA p-levels from MANOVA analysis are presented for each variable. Univariate ANOVA p-levels are listed
first by the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time or group x time interaction with significance indicated by the following
super/subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: † represents p <0.05 difference from baseline value,
Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post. IL interleukin, RFT race finish time, G group p-level, T time p-level,
G x T interaction; q quadratic p-level, L linear p-level
Page 17 of 23
Variable
Lymphocytes (K/uL)
WBC (K/uL)
Group
GRAN (K/uL)
60-min Post
24-hr Post
48-hr Post
Group Mean
p-value (GG)
p-value (WSC)
P
1.83 ± 0.58
2.50 ± 0.81
1.47 ± 0.54
2.04 ± 0.69
2.26 ± 0.35
2.02 ± 0.11
G = 0.732
1.82 ± 0.53
2.63 ± 0.72
1.43 ± 0.25
1.75 ± 0.45
2.18 ± 0.46
1.96 ± 0.14
T <0.001*
Tq = 0.013*
G X T = 0.404
G X TL = 0.905
†
†Ψ
Ψ◊
†Ψ◊#
RFT Covariate
p-value (WSC)
G = 0.414
Tq = 0.509
Time Mean
1.83 ± 0.11
2.56 ± 0.15
1.90 ± 0.12
2.22 ± 0.08
P
5.93 ± 1.45
6.54 ± 1.71
12.61 ± 3.39^†Ψ
6.64 ± 1.84◊
5.14 ± 0.84
7.37 ± 0.29
G = 0.314
TC
5.83 ± 1.50
6.85 ± 1.61
10.80 ± 3.40†Ψ
5.73 ± 1.20◊
5.33 ± 1.05
6.91 ± 0.35
T <0.001*
Tq <0.001*
TL = 0.613
†Ψ
6.18 ± 0.32◊
5.24 ± 0.18†Ψ◊#
G X T = 0.223
G X Tq = 0.162
G X Tq = 0.500
◊
†Ψ◊#
5.88 ± 0.29
†
6.70 ± 0.33
1.45 ± 0.09
11.71 ± 0.66
†
P
0.45 ± 0.14
0.53 ± 0.20
0.67 ± 0.23
0.49 ± 0.19
1.10 ± 0.25
0.65 ± 0.03
G = 0.477
0.43 ± 0.11
0.61 ± 0.19†
0.54 ± 0.15
0.40 ± 0.10Ψ
1.10 ± 0.32†Ψ◊#
0.61 ± 0.04
T <0.001*
TL = 0.022*
G X T = 0.276
G X Tq = 0.388
†
†
Ψ◊
†Ψ◊#
G X TL = 0.200
G = 0.398
TC
G = 0.607
Tq = 0.495
Time Mean
0.44 ± 0.03
0.57 ± 0.04
0.44 ± 0.03
1.10 ± 0.06
P
3.59 ± 1.07
3.53 ± 1.04
10.49 ± 3.49^†Ψ
4.09 ± 1.28◊
1.76 ± 0.59†Ψ◊#
4.69 ± 0.24
G = 0.349
TC
3.59 ± 1.41
3.64 ± 0.86
8.83 ± 3.35†Ψ
3.58 ± 0.98◊
2.05 ± 1.00◊
4.34 ± 0.29
T < 0.001*
Tq <0.001*
TL = 0.326
†Ψ
◊
G X T = 0.259
G X Tq = 0.168
G X Tq = 0.493
Time Mean
GM-CSF (pg/mL)
Pre-Run
TC
Time Mean
MID (K/uL)
Baseline
3.59 ± 0.24
3.58 ± 0.19
0.60 ± 0.04
9.66 ± 0.67
3.84 ± 0.23
1.90 ± 0.15†Ψ◊#
G X Tq = 0.562
G = 0.566
P
26.38 ± 41.92
25.49 ± 31.29
26.08 ± 34.72
22.64 ± 30.21
22.41 ± 29.72
24.60 ± 9.15
G = 0.485
TC
42.26 ± 47.28
37.37 ± 45.40
35.27 ± 46.54
29.52 ± 38.02
29.41 ± 36.03
34.77 ± 11.04
T = 0.056§
TL = 0.022*
Tq = 0.794
Time Mean
34.32 ± 8.64
31.43 ± 7.36
30.68 ± 7.81
26.08 ± 6.57†Ψ◊
25.91 ± 6.34†Ψ◊
G X T = 0.407
G X TL = 0.221
G X TL = 0.319
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 9 Markers of immune-related complete blood counts
G = 0.696
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the complete blood count immune response markers at each testing session during the
10 day intervention. MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.684). Univariate ANOVA p-levels from MANOVA analysis are presented for each variable. Univariate ANOVA
p-levels are listed first by the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time or group x time interaction with significance indicated
by the following super/subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents p <0.05 difference between groups, † represents p <0.05 difference from baseline value, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post. WBC
white blood cell, MID mid-range absolute count, GRAN granulocyte absolute count, GM-CSF granulocyte-macrophage colony-stimulating factor, RFT race finish time, G group p-level, T time p-level, G x T interaction,
q quadratic p-level, L linear p-level
Page 18 of 23
Variable
Group
Pre-Run
60-min Post
24-hr Post
Algo I (cm)
P
5.99 ± 2.94^
6.98 ± 3.35
6.44 ± 2.69
Algo II (cm)
Algo III (cm)
Ψ
48-hr Post
Ψ
5.95 ± 3.01
Ψ
TC
3.96 ± 2.15
6.43 ± 3.15
6.31 ± 3.43
5.98 ± 3.04
Time Mean
4.98 ± 0.52
6.71 ± 0.64Ψ
6.38 ± 0.59Ψ
5.96 ± 0.59Ψ
Group Mean
p-value (GG)
p-value (WSC)
RFT Covariate
p-value (WSC)
6.34 ± 0.66
G = 0.523
5.67 ± 0.80
T = 0.003*
Tq = 0.002*
TL = 0.440
G X T = 0.110
G X TL = 0.035*
G X TL = 0.028*
G = 0.660
P
5.02 ± 2.55
5.77 ± 2.91
5.58 ± 2.56
4.78 ± 3.02
5.29 ± 0.60
G = 0.393
TC
4.15 ± 2.66
5.12 ± 3.01
4.51 ± 3.10
4.08 ± 2.30
4.47 ± 0.72
T = 0.122
Tq = 0.013*
TL = 0.229
G X T = 0.921
G X Tq = 0.889
G X Tq = 0.458
5.38 ± 0.67
G = 0.098§
3.58 ± 0.80
T < 0.001*
Tq < 0.001*
TL = 0.508
G X T = 0.058§
G X Tq = 0.053§
G X Tq = 0.257
Time Mean
4.59 ± 0.51
5.45 ± 0.58
5.05 ± 0.55
4.43 ± 0.54
P
4.65 ± 3.04^
6.41 ± 2.91^Ψ
6.04 ± 2.90^Ψ◊
4.41 ± 2.90◊#
Ψ
Ψ
TC
2.59 ± 2.45
4.43 ± 2.89
3.48 ± 2.92
3.84 ± 3.11
Time Mean
3.62 ± 0.55
5.42 ± 0.57Ψ
4.76 ± 0.57Ψ
4.12 ± 0.59◊
G = 0.847
G = 0.226
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Table 10 Quadriceps muscle soreness perception
Individual group and time data expressed as means ± SD, while group effects are presented as means ± SEM. Data represents the participant soreness perception in the quadriceps muscle group at each testing
session during the 10 day intervention. MANOVA analysis revealed overall Wilks’ Lambda time (p <0.001) and group x time (p = 0.199). Univariate ANOVA p-levels from MANOVA analysis are presented for each variable.
Univariate ANOVA p-levels are listed first by the Greenhouse-Geisser (GG) analysis and then by the within-subjects contrasts (WSC) to demonstrate the potential shape of the time or group x time interaction with
significance indicated by the following super/subscripts: * indicates p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents p
<0.05 difference between groups, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents p <0.05 difference from 24-hr post. Algo I Algometer location #1: Vastus
Medalis 1/4, Algo II Algometer location #2: Vastus Lateralis 1/4, Algo III Algometer location #3: Vastus Lateralis 1/2, RFT race finish time, G group p-level, T time p-level, G x T interaction, q quadratic p-level, L
linear p-level
Page 19 of 23
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
Page 20 of 23
Fig. 7 Perceptions of muscle soreness. Data expressed as means ± SE and significance indicated by the following super/subscripts: * indicates
p <0.05 p-level significance, § indicates p <0.10 p-level significance. LSD post hoc analysis is indicated by the following superscripts: ^ represents
p <0.05 difference between groups, Ψ represents p <0.05 difference from pre-run, ◊ represents p <0.05 difference from 60-min post, # represents
p <0.05 difference from 24-hr post
compared to placebo. The greater antioxidant bioavailability from functional foods, such as tart cherries, containing
high levels of flavonoids and anthocyanins [43], has been
hypothesized to beneficially support endogenous antioxidant systems following strenuous exercise and excessive
ROS-production. Howatson et al. [44] analyzed plasma
TAS following a full marathon in trained endurance runners, and found that TAS was significantly greater in the
tart cherry supplemented group compared to control up
to 48-h post-race [7, 28, 38]. Unlike the tart cherry group,
TAS levels dropped below baseline 48-h following endurance exercise in the placebo group as they failed to
maintain redox balance. This discrepancy between supplementation groups demonstrates possible tart cherry antioxidant effectiveness on excessive ROS production during
bouts of endurance exercise [7]. Similar to the recovery
findings of Howatson et al. [44], the current study revealed a linear increase in TAS activity culminating in a
48-h recovery TAS activity that was greater in the tart
cherry group compared to placebo. This demonstrates a
potential short-term antioxidant effect of powdered tart
cherry consumption surrounding a single endurance challenge with better achievement of redox balance compared
to placebo supplementation.
Additional redox research has reported changes in
exercise-induced oxidative stress utilizing TBARS analyses to measure lipid hydroperoxidation decomposition
products over time. Supplementing with a tart cherry juice
blend or placebo for 8-d surrounding a marathon run,
Howatson et al. [28] demonstrated significantly lower
TBARS levels 48-h post-marathon in the tart cherry supplemented group versus placebo. In coordination with
Howatson et al. [28], Pilaczynska-Szczesniak et al. [26]
reported significantly attenuated serum TBARS levels at
1-min and 24-h post-2,000 m incremental rowing test
following 4-wk of chokeberry supplementation in trained
rowing athletes compared to those supplemented with a
placebo. In two more recent studies within the same
trained rowing athlete population used by PilaczynskaSzczesniak et al. [26], Skarpanska-Stejnborn et al. [45, 46]
reported no differences in post-2,000 m incremental rowing test TBARS levels following 4-5-wk of supplementation with either Rhodiola rosea L. extract or artichoke
extract. Contradictory outcomes across several studies
may be due to mode of exercise, training and nutrition
status, and duration of supplementation. Further, evidence
in the literature utilizing lipid peroxidation (TBARS assays) analysis has presented a potential lack of oxidative
damage detection specificity in human studies that may
also explain the variability in results between the current
and previous studies [4, 7, 35, 47].
As a highly reactive oxide metabolite of nitric oxide,
peroxynitrate-bound tyrosine residues forming nitrotyrosine (NT) was measured by Sureda et al. [48] following
supplementation of vitamin C + vitamin E surrounding a
half-marathon. Suerda et al. [48] reported a significant
increase in NT immediately post-race and 3-h post-race
in the placebo group compared to the vitamin C + vitamin
E supplemented group, indicating that antioxidant supplementation may have a dampening effect on oxidation of
nitrogen-containing compounds with endurance exercise.
The current study, however, reported no differences in
NT levels over the study protocol or between supplementation groups. The outcome inconsistency may also be attributable to the differences in the antioxidant supplement
and bioavailability, thus exhibiting a potential mechanistic
variability in whole fruit-derived versus extracted antioxidant supplements (e.g. vitamins C and E).
The effect of phytochemical or vitamin containing antiinflammatory supplements on the perception of muscle
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
soreness after an endurance exercise challenge is inconsistent within the literature. Close et al. [20] acutely
supplemented subjects with either ascorbic acid or a placebo surrounding an eccentrically braked endurance trial,
where physically active subjects ran downhill continuously
for 30-min. Close et al. [20] reported no significant differences in VAS pain ratings nor pressure algometry between
groups up to 14-d post-exercise on six lower extremity
locomotion muscle groups. With no effect on post-aerobic
exercise delayed onset muscle soreness (DOMS) in addition
to previous evidence in the literature, Close et al. [20] suggested a dissociation between post-exercise ROS production and DOMS. Following a marathon running event and
a bout of high intensity stochastic cycling using a similar
200 mm VAS protocol, Howatson et al. [28] and Bell et al.
[35] respectively, reported no difference in DOMS ratings
between Montmorency tart cherry juice supplementation
and placebo up to 72-h post-exercise. Within the current
study, no quadriceps soreness differences were detected
between groups over the three recovery time points. Due to
the significant difference in pre-run medial quadriceps soreness between supplementation groups, delta changes calculated from pre-run revealed greater recovery medial muscle
soreness with tart cherry supplementation compared to placebo. Without a baseline measure of quadriceps soreness
perception and a subject training load record surrounding
data collection, it is difficult to rationalize the pre-run
muscle soreness discrepancy. However, the variability in
soreness perceptions across muscle groups within the
current study compared to previous research may also be
due to the disparity in measurement protocol, supplements,
exercise modality, and/or subject pool training status.
Measurement of muscle soreness perception in the present
study utilizing both an algometer and a GRPS was implemented to help ameliorate the purely subjective nature of a
VAS as the only measure of pain or soreness.
The strengths of the current study revolve around the
cohort of soreness measures and hemodynamic markers
that contribute a more comprehensive analysis to the existing body of published literature. Some of the more recent
endurance-based tart cherry supplementation research
studies have investigated phytonutrient effectiveness on a
comprehensive panel of hemodynamic markers, which will
allow for parallels to be drawn to the powdered tart cherry
supplement used in the current study. The current study
did not enter the study cohort into a previously established
race competition, but rather created a half-marathon race
exclusively for the study. The utilization of this supplement within a trained population demonstrated its
effectiveness under normative training, diet, and performance conditions. Potential limitations and weakness of the
current study should also be considered. The placebocontrol matched design of this study was effective in
equalizing study subject exposure to the conditions of the
Page 21 of 23
half-marathon irrespective of supplement group. However,
compared to previous research implementing a cross-over
design, some variability associated with subject pairing
may have been possible. Differences in aerobic state of
training beyond the study inclusion/exclusion criteria may
also have been a source of variability in study cohort
recruitment. Due to the large number of hemodynamic
markers measured in this study, the five selected time
points of blood draws over the course of the experimental
period may have not fully represented the pharmacokinetic profile of each marker. The major overriding
strength of the current study is that this is the first study
to be conducted utilizing a powdered form of tart cherries
rather than a juice or concentrate.
Conclusions
The findings of the current study revealed that consumption of a Montmorency powdered tart cherry supplement
7-d before, the day of, and 2-d after completing an endurance running challenge, appears to be an effective dietary
supplement that may help attenuate post-run markers of
muscle catabolism and physiological stress in aerobically
trained individuals. Attenuation of inflammatory markers
over the 48-h recovery also demonstrates significant promise with powdered tart cherry supplementation. Coupled
with the dampening of the inflammatory response, the
powdered tart cherry subjects seemed to better maintain
post-run redox balance compared to placebo supplemented
subjects. The initial effectiveness on aerobic performance,
serum markers of muscle catabolism, physiological stress,
and inflammatory mechanisms coupled with a more stable
post-run redox balance potentially indicates a reduction in
secondary muscle damage as a result of powdered tart
cherry supplementation. Despite inconclusive evidence
surrounding the perceptions of medial quadriceps soreness,
the primary findings of the current study demonstrate that
powdered tart cherry supplementation in endurancetrained individuals provides similar benefits as previously
studied tart cherry juices or concentrates following acute
bouts of aerobic-based exercise.
Acknowledgements
We would like to thank the subjects that participated in this study as well as all
the students and laboratory assistants, particularly Nicholas Barringer, Jeremy
Carter, Yanghoon Peter Jung, Adriana Coletta, Brittany Sanchez, Minye Cho, and
Majid Koozehchian, in the Exercise & Sport Nutrition Laboratory at Texas A&M
University who assisted with data collection. We would also like to thank Mike
Vaughn and Katherine Kelly for their valuable assistance in sample analysis.
Authors’ contributions
KL assisted in designing the study, writing the grant, study coordination, data
collection, data analysis, and manuscript preparation. RD, CG, AO, and SS assisted
in data collection and sample analysis. EG assisted with data collection, sample
analysis, and review of dietary inventories as the RD on staff. CR is the director of
the exercise and sport nutrition lab. MG assisted in research design and
consultation. SMT, SR, and SC assisted in study consultation. RBK (corresponding
author) assisted in the design of the study, data analysis, manuscript preparation,
Levers et al. Journal of the International Society of Sports Nutrition (2016) 13:22
obtained the grant, and served as study PI. All authors read and approved the
final manuscript.
17.
Competing interests
This study was funded by Anderson Global Group, LLC (Irvine, CA, USA) and
Shoreline Fruit, LLC (Traverse City, MI, USA) through an unrestricted research
grant to Texas A&M University. All researchers involved independently collected,
analyzed, and interpreted the results from this study and have no financial
interests concerning the outcome of this investigation. The results from this
study do not constitute endorsement by the authors and/or the institution
concerning the nutrients investigated.
Author details
1
Department of Health and Kinesiology, Exercise and Sport Nutrition
Laboratory, Texas A&M University, College Station, TX 77843-4243, USA.
2
Department of Nutrition and Food Science, Institute for Obesity Research
and Program Evaluation, Texas A&M University, College Station, TX
77843-4243, USA. 3Department of Health and Kinesiology, Human
Countermeasures Laboratory, Texas A&M University, College Station, TX
77843-4243, USA. 4Department of Health and Kinesiology, Applied Exercise
Science Laboratory, Texas A&M University, College Station, TX 77843-4243,
USA.
18.
19.
20.
21.
22.
23.
Received: 7 March 2016 Accepted: 11 May 2016
24.
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